Evolutionary Conceptual Clustering Based on Induced Pseudo-Metrics

2010 ◽  
pp. 257-280
Author(s):  
Nicola Fanizzi ◽  
Claudia d’Amato ◽  
Floriana Esposito
Keyword(s):  
Distance Measure ◽  
Concept Drift ◽  
Fitness Function ◽  
Description Logics ◽  
Optimization Method ◽  
Optimal Choice ◽  
Validity Indices ◽  
Evolutionary Operators ◽  
Clustering Validity ◽  
The Given

We present a method based on clustering techniques to detect possible/probable novel concepts or concept drift in a Description Logics knowledge base. The method exploits a semi-distance measure defined for individuals, that is based on a finite number of dimensions corresponding to a committee of discriminating features (concept descriptions). A maximally discriminating group of features is obtained with a randomized optimization method. In the algorithm, the possible clusterings are represented as medoids (w.r.t. the given metric) of variable length. The number of clusters is not required as a parameter, the method is able to find an optimal choice by means of evolutionary operators and a proper fitness function. An experimentation proves the feasibility of our method and its effectiveness in terms of clustering validity indices. With a supervised learning phase, each cluster can be assigned with a refined or newly constructed intensional definition expressed in the adopted language.

scholarly journals Efficient Computation of Fitness Function for Evolutionary Clustering

MENDEL ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 87-94 ◽  
Author(s):  
Sergey Muravyov ◽  
Denis Antipov ◽  
Arina Buzdalova ◽  
Andrey Filchenkov
Keyword(s):  
Evolutionary Algorithms ◽  
Optimization Problems ◽  
Fitness Function ◽  
Random Search ◽  
Efficient Computation ◽  
Function Computation ◽  
Clustering Problem ◽  
Evolutionary Clustering ◽  
Validity Indices ◽  
Clustering Validity

Evolutionary algorithms (EAs) are random search heuristics which can solve various optimization problems. There are plenty of papers describing different approaches developed to apply evolutionary algorithms to the clustering problem, although none of them addressed the problem of fitness function computation. In clustering, many clustering validity indices exist that are designed to evaluate quality of resulting points partition. It is hard to use them as a fitness function due to their computational complexity. In this paper, we propose an efficient method for iterative computation of clustering validity indices which makes application of the EAs to this problem much more appropriate than it was before.

scholarly journals Improved Backstepping Control of a DFIG based Wind Energy Conversion System using Ant Lion Optimizer Algorithm

2021 ◽  
Author(s):  
Zoubir Zeghdi ◽  
Linda Barazane ◽  
Youcef Bekakra ◽  
Abdelkader Larabi
Keyword(s):  
Fitness Function ◽  
Harmonic Distortion ◽  
Absolute Error ◽  
Optimization Method ◽  
Backstepping Control ◽  
Ant Lion Optimizer ◽  
Integral Time ◽  
Distortion Minimization ◽  
Ant Lion ◽  
Doubly Fed

In this paper, an improved Backstepping control based on a recent optimization method called Ant Lion Optimizer (ALO) algorithm for a Doubly Fed Induction Generator (DFIG) driven by a wind turbine is designed and presented. ALO algorithm is applied for obtaining optimum Backstepping control (BCS) parameters that are able to make the drive more robust with a faster dynamic response, higher accuracy and steady performance. The fitness function of the ALO algorithm to be minimized is designed using some indexes criterion like Integral Time Absolute Error (ITAE) and Integral Time Square Error (ITSE). Simulation tests are carried out in MATLAB/Simulink environment to validate the effectiveness of the proposed BCS-ALO and compared to the conventional BCS control. The results prove that the objectives of this paper were accomplished in terms of robustness, better dynamic efficiency, reduced harmonic distortion, minimization of stator powers ripples and performing well in solving the problem of uncertainty of the model parameter.

scholarly journals LEAN MANUFACTURING PROCESS PLANNING FOR 5 AXES CNC DRIVEN MILLING MACHINE

2019 ◽  
Vol 4 (1) ◽  
pp. 10-28
Author(s):  
Sándor Bodzás ◽  
Béla Krakkó
Keyword(s):  
Lean Manufacturing ◽  
Optimal Choice ◽  
Depth Of Cut ◽  
Milling Machine ◽  
Technological Parameters ◽  
Future State ◽  
Manufacturing Process Planning ◽  
Manufacturing Technologies ◽  
The Right ◽  
The Given

The aim of this publication is to determine the OEE (Overall Equipment Efficiency) indicator for 5 axes milling machine found at Diehl Aircabin Hungary Ltd. for the present and future state. Based on this value, the utilization of the machine for the given production amount can be calculated. With the optimal choice of the right production parameters (the number of cuts, feeding, depth of cut, etc.) greater productivity can be achieved i.e. the machine main time (time of cutting) will be less. The possibilities of the reduction of the machine time will be analysed and calculated. Setting of the appropriate technological parameters the machine main time could be decreased. The calculation of the machine main time will be determined for the most frequent manufacturing technologies.

A general trajectory optimization method for aircraft taxiing on flight deck of carrier

2018 ◽  
Vol 233 (4) ◽  
pp. 1340-1353 ◽  
Author(s):  
Yu Wu ◽  
Ning Hu ◽  
Xiangju Qu
Keyword(s):  
Optimization Algorithm ◽  
Trajectory Optimization ◽  
Fitness Function ◽  
Control Variable ◽  
Optimization Method ◽  
Operation Efficiency ◽  
Ground Motion Model ◽  
Aircraft System ◽  
Chicken Swarm Optimization ◽  
Flight Deck

Enhancing operation efficiency of flight deck has become a hotspot because it has an important impact on the fighting capacity of the carrier–aircraft system. To improve the operation efficiency, aircraft need taxi to the destination on deck with the optimal trajectory. In this paper, a general method is proposed to solve the trajectory optimization problem for aircraft taxiing on flight deck considering that the existing methods can only deal with the problem in some specific cases. Firstly, the ground motion model of aircraft, the collision detection strategy and the constraints are included in the mathematical model. Then the principles of the chicken swarm optimization algorithm and the generality of the proposed method are explained. In the trajectory optimization algorithm, several strategies, i.e. generation of collocation points, transformation of control variable, and setting of segmented fitness function, are developed to meet the terminal constraints easier and make the search efficient. Three groups of experiments with different environments are conducted. Aircraft with different initial states can reach the targets with the minimum taxiing time, and the taxiing trajectories meet all the constraints. The reason why the general trajectory optimization method is validated in all kinds of situations is also explained.

Minimization of the Vibration Energy of Thin-Plate Structures

1992 ◽  
Author(s):  
Katsumi Inoue ◽  
Dennis P. Townsend ◽  
John J. Coy
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Thin Plate ◽  
Optimization Method ◽  
Optimum Shape ◽  
Vibration Energy ◽  
Plate Structures ◽  
Constant Weight ◽  
Exciting Frequency ◽  
The Given

Abstract An optimization method is proposed to reduce the vibration of thin-plate structures. The method is based on a finite-element shell analysis, a modal analysis, and a structural optimization method. In the finite-element analysis, a triangular shell element with 18 degrees of freedom is used. In the optimization, the overall vibration energy of the structure is adopted as the objective function, and it is minimized at the given exciting frequency by varying the thickness of the elements. The technique of modal analysis is used to derive the sensitivity of the vibration energy with respect to the design variables. The sensitivity is represented by the sensitivities of both eigenvalues and eigenvectors. The optimum value is computed by the gradient projection method and a unidimensional search procedure under the constraint condition of constant weight. A computer code, based on the proposed method, is developed and is applied to design problems using a beam and a plate as test cases. It is confirmed that the vibration energy is reduced at the given exciting frequency. For the beam excited by a frequency slightly less than the fundamental natural frequency, the optimized shape is close to the beam of uniform strength. For the plate, the optimum shape is obtained such that the changes in thickness have the effect of adding a stiffener or a mass.

Automation Tool Preparation in the Conditions of Production

2015 ◽  
Vol 770 ◽  
pp. 739-743 ◽  
Author(s):  
A.S. Yuanyushkin ◽  
D.V. Lobanov ◽  
D.A. Rychkov
Keyword(s):  
Comparative Analysis ◽  
Rational Design ◽  
Economic Effect ◽  
Optimal Choice ◽  
Processing Efficiency ◽  
Time Required ◽  
The Given ◽  
High Processing ◽  
Selection Of

The key task of the tool manufacturing is to create or to choose such a type of tool, which would permit to provide high processing efficiency, the best tool`s workability and the quality of the machined surfaces with minimum expenses and resources. The optimal choice of the constructive tool modifications from a variety of options takes much time required for the preparation of the tool to work. To solve this problem, we have developed software that allows you to create, organize and carry out a comparative analysis of structural instruments in order to identify rational option for the given conditions of production. Ordering and selection of a rational design of the instrument is carried out in accordance with established procedures of modeling and comparative analysis of design solutions. Application software can reduce design time technological process by 80...90%, and get a substantial annual economic effect.

scholarly journals An Optimization Framework for Codes Classification and Performance Evaluation of RISC Microprocessors

Symmetry ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 938
Author(s):  
Syed Rameez Naqvi ◽  
Ali Roman ◽  
Tallha Akram ◽  
Majed M. Alhaisoni ◽  
Muhammad Naeem ◽  
...  
Keyword(s):  
Assembly Language ◽  
Optimization Method ◽  
Instruction Set ◽  
Mathematical Performance ◽  
Optimization Framework ◽  
And Performance ◽  
Reduced Instruction Set Computer ◽  
High Level ◽  
The Given ◽  
Primary Contribution

Pipelines, in Reduced Instruction Set Computer (RISC) microprocessors, are expected to provide increased throughputs in most cases. However, there are a few instructions, and therefore entire assembly language codes, that execute faster and hazard-free without pipelines. It is usual for the compilers to generate codes from high level description that are more suitable for the underlying hardware to maintain symmetry with respect to performance; this, however, is not always guaranteed. Therefore, instead of trying to optimize the description to suit the processor design, we try to determine the more suitable processor variant for the given code during compile time, and dynamically reconfigure the system accordingly. In doing so, however, we first need to classify each code according to its suitability to a different processor variant. The latter, in turn, gives us confidence in performance symmetry against various types of codes—this is the primary contribution of the proposed work. We first develop mathematical performance models of three conventional microprocessor designs, and propose a symmetry-improving nonlinear optimization method to achieve code-to-design mapping. Our analysis is based on four different architectures and 324,000 different assembly language codes, each with between 10 and 1000 instructions with different percentages of commonly seen instruction types. Our results suggest that in the sub-micron era, where execution time of each instruction is merely in a few nanoseconds, codes accumulating as low as 5% (or above) hazard causing instructions execute more swiftly on processors without pipelines.

scholarly journals A Validity Index for Fuzzy Clustering Based on Bipartite Modularity

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Yongli Liu ◽  
Xiaoyang Zhang ◽  
Jingli Chen ◽  
Hao Chao
Keyword(s):  
Fuzzy Clustering ◽  
Optimal Number ◽  
Experimental Results ◽  
Validity Index ◽  
Number Of Clusters ◽  
Validity Indices ◽  
Noise Data ◽  
Clustering Validity ◽  
Optimal Number Of Clusters

Because traditional fuzzy clustering validity indices need to specify the number of clusters and are sensitive to noise data, we propose a validity index for fuzzy clustering, named CSBM (compactness separateness bipartite modularity), based on bipartite modularity. CSBM enhances the robustness by combining intraclass compactness and interclass separateness and can automatically determine the optimal number of clusters. In order to estimate the performance of CSBM, we carried out experiments on six real datasets and compared CSBM with other six prominent indices. Experimental results show that the CSBM index performs the best in terms of robustness while accurately detecting the number of clusters.

Identification of the Cutting Forces Coefficients via Milling Process Simulation

2011 ◽  
Author(s):  
Sergey A. Voronov ◽  
Igor A. Kiselev ◽  
Maxim G. Yakovlev
Keyword(s):  
Cutting Forces ◽  
Chip Thickness ◽  
Element Model ◽  
Optimization Method ◽  
Milling Process ◽  
Force Model ◽  
Processed Material ◽  
A New Technique ◽  
The Mathematical Model ◽  
The Given

The paper is devoted to the description of a new technique (numerical and experimental) identification of the dependences between cutting forces and instantaneous chip thickness. It is required to measure only the cutting forces versus cutting conditions. Experimentally, for the given pair the processed material – the tool, coefficients of the cutting forces model are calculated by means of the optimization method (Nelder-Mead algorithm). The mathematical model of the milling process developed by authors on each step of the Nelder-Mead method is used for the process numerical simulation under given coefficients of the cutting force model. The elaborated numerical modeling algorithm allows investigating the dynamics and the kinematics of the milling process. The dynamic model of the tool, the algorithm of geometrical modeling of the instantaneous chip thickness, the finite element model of the detail are embedded into the whole model of the milling process.

A Novel Global Optimization Algorithm and Its Application to Airfoil Optimization

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
B. Yang ◽  
Q. Xu ◽  
L. He ◽  
L. H. Zhao ◽  
Ch. G. Gu ◽  
...  
Keyword(s):  
Global Optimization ◽  
Optimization Algorithm ◽  
Fitness Function ◽  
Optimization Method ◽  
The Novel ◽  
Global Optimization Algorithm ◽  
Low Velocity ◽  
Airfoil Optimization ◽  
The Difference ◽  
Optimization Efficiency

In this paper, a novel global optimization algorithm has been developed, which is named as particle swarm optimization combined with particle generator (PSO–PG). In PSO–PG, a PG was introduced to iteratively generate the initial particles for PSO. Based on a series of comparable numerical experiments, it was convinced that the calculation accuracy of the new algorithm as well as its optimization efficiency was greatly improved in comparison with those of the standard PSO. It was also observed that the optimization results obtained from PSO–PG were almost independent of some critical coefficients employed in the algorithm. Additionally, the novel optimization algorithm was adopted in the airfoil optimization. A special fitness function was designed and its elements were carefully selected for the low-velocity airfoil. To testify the accuracy of the optimization method, the comparative experiments were also carried out to illustrate the difference of the aerodynamic performance between the optimized and its initial airfoil.

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